Coupled neutronic-thermal–mechanical analysis of a medium temperature heat pipe cooled reactor

Medium temperature heat pipe cooled reactor (MTR) can better address problems faced in tradition heat pipe cooled reactor such as challenges in high-temperature corrosion-resistant material, possible startup failure accidents and high steel monolithic thermal stress. The unique advantages of MTR include excellent startup performance, high transient negative temperature coefficient, low monolithic thermal stress, etc. This study works on MTR by adopting a hexagonal uranium zirconium hydride fuel assembly structure with a central mercury heat pipe in replace of the previous fuel pin assembly. A coupled neutronic-thermal–mechanical strategy is discussed with an emphasis on iteration schemes and geometry reconstruction. This method is then applied for core physics analysis, shield design, thermal-mechanics analysis of fuel assemblies, and heat pipe failure analysis. A systematic comparison between the previous design and this work is also discussed. According to the results, the total mass of the core decreased significantly, and specific power increased by 10 % compared to the previous design (Li et al., 2022). A high transient negative temperature coefficient ensures excellent self-regulation ability in the face of accidents. The possibility of fracture is almost eliminated during normal operating conditions, and fuel assembly can be maintained at the normal operating temperature under one heat pipe failure accident. This MTR design is equipped with very high inherent safety. This work provides references to the future design of MTR. © 2024 Elsevier B.V.